(marstacimab-hncq)

Prescribing Information
Download Prescribing Information

8 USE IN SPECIFIC POPULATIONS

8 USE IN SPECIFIC POPULATIONS

  

8.1 Pregnancy

Risk Summary
Based on its mechanism of action, HYMPAVZI may cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1)]. There are no available data on HYMPAVZI use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage or other adverse maternal or fetal outcomes. Female animal reproduction studies have not been conducted with HYMPAVZI. Although there are no data on marstacimab‑hncq, monoclonal antibodies can be actively transported across the placenta, and marstacimab‑hncq may cause fetal harm.

The background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

8.2 Lactation

Risk Summary
There are no data on the presence of marstacimab‑hncq in either human or animal milk, the effects on the breastfed child, or the effects on milk production.

Endogenous maternal IgG and monoclonal antibodies are known to be present in human milk. The effects of local gastrointestinal exposure and limited systemic exposure in the breastfed child to marstacimab‑hncq are unknown.

The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for HYMPAVZI and any potential adverse effects on the breastfed infant from HYMPAVZI or from the underlying maternal condition.

8.3 Females and Males of Reproductive Potential

HYMPAVZI may cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].

Pregnancy Testing
Verify the pregnancy status of females of reproductive potential prior to initiating HYMPAVZI treatment.

Contraception

Females
Advise female patients of reproductive potential to use effective contraception during treatment with HYMPAVZI and for 2 months after the last dose.

8.4 Pediatric Use

The safety and effectiveness of HYMPAVZI to prevent or reduce the frequency of bleeding episodes in hemophilia A or B with and without inhibitors have been established in pediatric patients 6 years of age and older [see Clinical Studies (14.1, 14.2, 14.3)]. Use of HYMPAVZI in pediatric patients for this indication is supported by evidence from two open‑label, multi‑center studies (BASIS and BASIS KIDS). These two studies treated 56 adolescents (12 to less than 18 years of age). BASIS KIDS treated 68 children (6 to less than 12 years of age). Efficacy and adverse reaction profile were comparable between pediatric patients and adults [see Adverse Reactions (6.1) and Clinical Studies (14.1, 14.2, 14.3)]. Differences observed in steady‑state pharmacokinetic (PK) exposures between pediatric patients and adults were mostly accounted for by body weight [see Clinical Pharmacology (12.3)].

The safety and effectiveness of HYMPAVZI have not been established in pediatric patients younger than 6 years of age.

8.5 Geriatric Use

Two patients 65 years of age and older were enrolled in the clinical studies for hemophilia A or B with or without inhibitors [see Clinical Studies (14.1, 14.2)]. Clinical studies of HYMPAVZI did not include sufficient numbers of subjects 65 years of age and over to determine whether they respond differently from younger subjects.

Medication Guide

MEDICATION GUIDE

     

This Patient Information has been approved by the U.S. Food and Drug Administration.          Revised: 6/2026

PATIENT INFORMATION

HYMPAVZI® (him-PAV-zee)

(marstacimab-hncq)

injection, for subcutaneous use

Important information:

•
Before you start using HYMPAVZI, it is very important to talk to your healthcare provider about using factor VIII and factor IX products or bypassing agents (products that help blood clot but work in a different way than HYMPAVZI).
•
Your healthcare provider may prescribe factor VIII, factor IX medicines, or bypassing agents to treat episodes of breakthrough bleeding during your treatment with HYMPAVZI. Carefully follow your healthcare provider’s instructions regarding when to use these medicines and the prescribed dose during your treatment with HYMPAVZI. Do not use additional doses of HYMPAVZI to treat breakthrough bleeds.

What is HYMPAVZI?

HYMPAVZI is a prescription medicine used regularly to prevent or reduce the frequency of bleeding episodes in adults and children 6 years of age and older with:

•
hemophilia A with or without factor VIII inhibitors, or
•
hemophilia B with or without factor IX inhibitors.

It is not known if HYMPAVZI is safe and effective in people receiving ongoing Immune Tolerance Induction (ITI).

It is not known if HYMPAVZI is safe and effective in children younger than 6 years of age.

Before using HYMPAVZI, tell your healthcare provider about all of your medical conditions, including if you:

•
have a planned surgery. Your healthcare provider may stop treatment with HYMPAVZI before your surgery. Talk to your healthcare provider about when to stop using HYMPAVZI and when to start it again if you have a planned surgery.
•
have a severe short-term (acute) illness such as an infection or injury.
•
have been told that you have a risk for blood clots.
•
are pregnant or plan to become pregnant. HYMPAVZI may harm your unborn baby.
 
Females who are able to become pregnant:
o
Your healthcare provider will do a pregnancy test before you start your treatment with HYMPAVZI.
o
Use effective birth control (contraception) during treatment with HYMPAVZI and for 2 months after the last dose of HYMPAVZI.
o
Tell your healthcare provider right away if you become pregnant or think that you may be pregnant during treatment with HYMPAVZI.
•
are breastfeeding or plan to breastfeed. It is not known if HYMPAVZI passes into your breast milk.

Tell your healthcare provider about all the medicines you take, including prescription medicines, over‑the‑counter medicines, vitamins, and herbal supplements.

Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

How should I use HYMPAVZI?

See the detailed “Instructions for Use” that comes with your HYMPAVZI for information on how to inject a dose of HYMPAVZI, and how to properly throw away (dispose of) used HYMPAVZI prefilled syringe or HYMPAVZI prefilled pen.

•
Use HYMPAVZI exactly as prescribed by your healthcare provider.
•
Your healthcare provider will provide instructions for stopping (discontinuing) your current treatment when switching from factor- or non-factor-based medicines or bypassing agents to HYMPAVZI.
•
HYMPAVZI comes in two different strengths in a single-dose prefilled syringe or single-dose prefilled pen.
•
HYMPAVZI is given as an injection under your skin (subcutaneous injection) by you or your caregiver.
•
People 12 years of age and older, or their caregiver may inject HYMPAVZI if your healthcare provider decides that it is appropriate. Your healthcare provider should show you or your caregiver how to inject HYMPAVZI before the first injection.
•
Do not inject yourself or someone else until you have been shown how to inject HYMPAVZI.
•
Inject HYMPAVZI 1 time a week on the same day each week. Inject HYMPAVZI at any time of day.
•
Dosing for adults and children 12 years of age and older:
o
Your first dose (loading dose) of HYMPAVZI is 300 mg (two 150 mg injections). Then you will inject a weekly (maintenance) dose as prescribed by your healthcare provider.
o
If you miss a maintenance dose of 150 mg of HYMPAVZI:
▪
Give the dose as soon as possible before the day of your next scheduled dose, and then continue with your usual weekly dosing schedule. You may inject your next dose at your regularly scheduled time or continue dosing based on the new day you injected your missed dose. In case you are not sure when to inject HYMPAVZI, call your healthcare provider.
▪
If more than 13 days have passed since your last dose was given, you will need to restart with a loading dose. Call your healthcare provider right away for dosing instructions.
o
If you miss 1 or more doses of maintenance dose of 300 mg of HYMPAVZI:
▪
Give a dose as soon as possible, and then continue with your usual weekly dosing schedule. You may inject your next dose at your regularly scheduled time or continue dosing based on the new day you injected your missed dose. In case you are not sure when to inject HYMPAVZI, call your healthcare provider.
•
Dosing for children 6 years to less than 12 years of age:
o
Your first dose (loading dose) of HYMPAVZI is 150 mg (one 150 mg injection or two 75 mg injections) as prescribed by your healthcare provider. Then you will inject a weekly (maintenance) dose as prescribed by your healthcare provider.
o
If you miss a maintenance dose of 75 mg of HYMPAVZI:
▪
Give the dose as soon as possible before the day of your next scheduled dose, and then continue with your usual weekly dosing schedule. You may inject your next dose at your regularly scheduled time or continue dosing based on the new day you injected your missed dose. In case you are not sure when to inject HYMPAVZI, call your healthcare provider.
▪
If more than 13 days have passed since your last dose was given, you will need to restart with a loading dose. Call your healthcare provider right away for dosing instructions.
o
If you miss 1 or more doses of maintenance dose of 150 mg of HYMPAVZI:
▪
Give a dose as soon as possible, and then continue with your usual weekly dosing schedule. You may inject your next dose at your regularly scheduled time or continue dosing based on the new day you injected your missed dose. In case you are not sure when to inject HYMPAVZI, call your healthcare provider.
•
If you inject too much HYMPAVZI, call your healthcare provider or the Poison Help Line at 1-800-222-1222 or go to the nearest hospital emergency room right away.

What are the possible side effects of HYMPAVZI?

HYMPAVZI may cause serious side effects, including:

•
blood clots (thromboembolic events). HYMPAVZI may increase the risk for your blood to clot in blood vessels in your arm, leg, lung, or head and can be life-threatening. Blood clots have happened in people using HYMPAVZI. You may have an increased risk of blood clots if you have certain risk factors. Stop using HYMPAVZI and get medical help right away if you develop any of these signs or symptoms of blood clots:
o
swelling or pain in arms or legs
o
redness or discoloration in your arms or legs
o
shortness of breath
o
pain in chest or upper back
o
fast heart rate
o
cough up blood
o
feel faint
o
headache
o
numbness in your face
o
eye pain or swelling
o
trouble seeing
•
allergic reactions. HYMPAVZI may cause allergic reactions, including rash and itching. Stop using HYMPAVZI and get medical help right away if you develop any of the following symptoms of a severe allergic reaction:
o
swelling of your face, lips, mouth, or tongue
o
trouble breathing
o
wheezing
o
dizziness or fainting
o
fast heartbeat or pounding in your chest
o
sweating

The most common side effects of HYMPAVZI include:

•
swelling, hardening, redness, bruising, bleeding, and pain at injection site
•
headache
•
fever
•
joint pain
•
diarrhea
•
itching
•
rash

These are not all of the possible side effects of HYMPAVZI.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

How should I store HYMPAVZI?

•
Store HYMPAVZI in a refrigerator at 36°F to 46°F (2°C to 8°C).
•
Store HYMPAVZI in the original carton to protect from light.
•
If needed, HYMPAVZI may be stored one time at room temperature up to 86°F (30°C) in its original carton for up to 7 days. Do not return HYMPAVZI to the refrigerator after storing at room temperature.
•
Throw away (dispose of) HYMPAVZI that has been left out of the refrigerator for more than 7 days.
•
Do not freeze HYMPAVZI.
•
Do not shake HYMPAVZI.

Keep HYMPAVZI and all medicines out of the reach of children.

General information about the safe and effective use of HYMPAVZI.

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use HYMPAVZI for a condition for which it was not prescribed. Do not give HYMPAVZI to other people, even if they have the same symptoms that you have. It may harm them. You can ask your pharmacist or healthcare provider for information about HYMPAVZI that is written for health professionals.

What are the ingredients in HYMPAVZI?

Active ingredient: marstacimab‑hncq

Inactive ingredients: edetate disodium, histidine, L-histidine monohydrochloride, polysorbate 80, sucrose, and water for injection

This product's labeling may have been updated. For the most recent prescribing information, please visit www.pfizer.com.

Pfizer logo
US License No. 2001
Distributed by: Pfizer Labs, Division of Pfizer Inc., New York, NY 10001
LAB-1575-3.0
For more information, go to website www.HYMPAVZI.com or call 1-800-438-1985.

Additional Resources

Chat online with Pfizer Medical Information regarding your inquiry on a Pfizer medicine or vaccine.

Speak with a Pfizer Medical Information Professional regarding your Pfizer medicine or vaccine inquiry.

Available 9AM-5PM ET Monday to Friday; excluding holidays.

 

Submit a medical question for a Pfizer medicine or a vaccine. 

The submission will be reviewed during our standard business hours.

To report an adverse event related to a Pfizer product and you are not part of a clinical trial* for this medication, click the link below to submit your information: 
Pfizer Safety Reporting Site

*If you are involved in a clinical trial for either product, adverse events should be reported to your coordinating study site.

If you cannot use the above website to report an adverse event related to a Pfizer medication, please call (800) 438-1985.

You may also contact the U.S. Food and Drug Administration (FDA) directly to report adverse events or product quality concerns either online at www.fda.gov/medwatch or by calling (800) 332-1088.